A number of methods exist for the estimation of abdominal obesity, ranging from waist-to-hip ratio to computed tomography (CT). Although dual-energy X-ray absorptiometry (DXA) was originally used to measure bone density and total body composition, recent improvements in software allow it to determine abdominal fat mass. Sixty-five men and women aged 18-72 yr participated in a series of studies to examine the validity and reliability of the DXA to accurately measure abdominal fat. Total body fat and abdominal regional fat were measured by DXA using a Lunar DPX-IQ. Multislice CT scans were performed between L1 and L4 vertebral bodies (region of interest) using a Picker PQ5000 CT scanner, and volumetric analyses were carried out on a Voxel Q workstation. Both abdominal total tissue mass (P = 0.02) and abdominal fat mass (P < 0.0001) in the L1-L4 region of interest were significantly lower as measured by DXA compared with multislice CT. However, Bland-Altman analysis demonstrated good concordance between DXA and CT for abdominal total tissue mass (i.e., limits of agreement = -1.56-2.54 kg) and fat mass (i.e., limits of agreement = -0.40-1.94 kg). DXA also showed excellent reliability among three different operators to determine total, fat, and lean body mass in the L1-L4 region of interest (intraclass correlations, R = 0.94, 0.97, and 0.89, respectively). In conclusion, the DXA L1-L4 region of interest compared with CT proved to be both reliable and accurate method to determine abdominal obesity.

CT and PET are widely used to characterize solitary pulmonary nodules (SPNs). However, most CT accuracy studies have been performed with outdated technology and methods, and previous PET studies have been limited by small sample sizes and incomplete masking. Our objective was to compare CT and PET accuracy in veterans with SPN. Methods: Between January 1999 and June 2001, we recruited 532 participants with SPNs newly diagnosed on radiography and untreated. The SPNs were 7-30 mm. All patients underwent 18 F-FDG PET and CT. A masked panel of 3 PET and 3 CT experts rated the studies on a 5-point scale. SPN tissue diagnosis or 2-y follow-up established the final diagnosis. Results: A definitive diagnosis was established for 344 participants. The prevalence of malignancy was 53%. The average size was 16 mm. Likelihood ratios (LRs) for PET and CT results for combined ratings of either definitely benign (33% and 9% of patients, respectively) or probably benign (27% and 12%) were 0.10 and 0.11, respectively. LRs for PET and CT results for combined ratings of indeterminate (1% and 25%), probably malignant (21% and 39%), or definitely malignant (35% and 15%) were 5.18 and 1.61, respectively. Area under the receiver operating characteristic curve was 0.93 (95% confidence interval, 0.90-0.95) for PET and 0.82 (95% confidence interval, 0.77-0.86) for CT (P , 0.0001 for the difference). PET inter-and intraobserver reliability was superior to CT. Conclusion: Definitely and probably benign results on PET and CT strongly predict benign SPN. However, such results were 3 times more common with PET. Definitely malignant results on PET were much more predictive of malignancy than were these results on CT. A malignant final diagnosis was approximately 10 times more likely than a benign final diagnosis in participants with PET results rated definitely malignant.

FDG-PET scanning detected mediastinal disease in two patients (17%) with advanced-stage head and neck squamous cell carcinoma that was not identified with conventional imaging techniques. PET imaging seems to have significant potential in the detection of occult metastatic disease, particularly in the mediastinal lymphatics.

Failures of communication, documentation errors, and various system failures may lead to an untoward outcome for the patient. We devised a simple system to ensure that significant unexpected findings on imaging received appropriate attention. An additional level of redundancy has increased the probability of optimal patient outcome.

With the use of new sonographic technology, we have observed that the echogenicity of kidneys is often equal to that of the liver in patients in whom there is no evidence of renal disease; this observation conflicts with the generally accepted notion that a normal kidney is always less echogenic than the liver. In order to reassess renal echogenicity as an indicator of disease, three experienced radiologists blindly reviewed the sonograms of the right kidney and liver in 153 patients. The prevalence of renal disease was 26% (40/153). Accepted sonographic criteria for abnormal renal echogenicity (kidney echogenicity greater than or equal to liver) were neither sensitive (62%) nor specific (58%) for renal disease, with a positive predictive value of 35%. Most of these inaccuracies occurred because 43 (72%) of 60 patients in whom renal echogenicity was equal to that of liver had normal renal function. If stricter criteria for abnormality were adopted (kidney echogenicity greater than liver), specificity (96%) and positive predictive value (67%) rose; however, sensitivity was only 20%. We conclude that renal echogenicity equal to the echogenicity of liver is not a good indicator of disease. Use of stricter criteria (kidney echogenicity greater than liver) provides a specific but insensitive test.